Transmission for vehicle

ABSTRACT

A transmission for a vehicle may include a first planetary gear set, a second planetary gear set, a third, planetary gear set, and a fourth planetary gear set each including three rotary elements, and a plurality of friction members, in which the friction members are connected to at least one or more of the rotary elements of the planetary gear sets and control rotation of the rotary elements.

CROSS REFERENCE TO RELATED APPLICATION

The present application claims priority to Korean Patent ApplicationNumber 10-2015-0081515 filed Jun. 9, 2015, the entire contents of whichis incorporated herein for all purposes by this reference.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a transmission for a vehicle that canimprove fuel efficiency by implementing multiple steps of shifting andimprove vehicle driving comfort by using operating points in a low RPMrange of an engine.

Description of Related Art

Recently, increasing oil prices have caused vehicle manufacturers allover the world to rush into infinite competition. Particularly in thecase of engines, manufacturers have been pursuing efforts to reduce theweight and improve fuel efficiency of vehicles by reducing engine size,etc.

As for an automatic transmission, there are various methods of improvingfuel efficiency, and operability and competitiveness in fuel efficiencycan both be secured by implementing multiple steps of shifting.

However, when the shift ranges increase, the number of parts in anautomatic transmission also increases, so the automatic transmission maybe difficult to mount, the manufacturing cost and weight may beincreased, and power transmission efficiency may be deteriorated.

Accordingly, in order to increase the effect of improving fuelefficiency through multiple steps of shifting, it may be important todevelop a gear train structure that can achieve maximum efficiency withfewer parts.

The information disclosed in this Background of the Invention section isonly for enhancement of understanding of the general background of theinvention and should not be taken as an acknowledgement or any form ofsuggestion that this information forms the prior art already known to aperson skilled in the art.

BRIEF SUMMARY

Various aspects of the present invention are directed to providing atransmission for a vehicle that can improve fuel efficiency byimplementing multiple steps of shifting and improve vehicle drivingcomfort by using operating points in a low RPM range of an engine.

According to various aspects of the present invention, a transmissionfor a vehicle may include a first planetary gear set, a second planetarygear set, a third, planetary gear set, and a fourth planetary gear seteach including three rotary elements, and a plurality of frictionmembers, in which the first planetary gear set may include a firstrotary element connected to an input shaft, a second rotary elementoperating as a selectively-fixed element and selectively connected witha third rotary element of the third planetary gear set; and a thirdrotary element connected with a second rotary element of the secondplanetary gear set, the second planetary gear set may include a firstrotary member operating as a fixed element, the second rotary elementselectively connected to an output shaft, and a third rotary elementselectively connected with a third rotary element of the fourthplanetary gear set, the third planetary gear set may includes a firstrotary element selectively connected with a first rotary element of thefourth planetary gear set, a second rotary element connected to an inputshaft, and a third rotary element connected to a second rotary elementof the fourth planetary gear set, the fourth planetary gear set mayinclude the second rotary element connected to an output shaft, and thefriction members may be connected to at least one or more of the rotaryelements of the planetary gear sets and control rotation of the rotaryelements.

In the first planetary gear set, the first rotary element may be a firstsun gear, the second rotary element may be a first carrier, and thethird rotary element may be a first ring gear, in the second planetarygear set, the first rotary element may be a second sun gear, the secondrotary element may be a second carrier, and the third rotary element maybe a second ring gear, in the third planetary gear set, the first rotaryelement may be a third sun gear, the second rotary element may be athird carrier, and the third rotary element may be a third ring gear,and in the fourth planetary gear set, the first rotary element may be afourth sun gear, the second rotary element may be a fourth carrier, andthe third rotary element may be a fourth ring gear.

The second rotary element of the first planetary gear set may beconnected to and disconnected from a transmission case by a thirdclutch, and the second rotary element of the first planetary gear setand the third rotary element of the third planetary gear set may beconnected to and disconnected from each other by a fourth clutch.

The first rotary element of the second planetary gear set may beconnected to a transmission case, the second rotary element of thesecond planetary gear set may be connected to and disconnected from theoutput shaft by a first clutch, and the third rotary element of thesecond planetary gear set and the third rotary element of the fourthplanetary gear set may be connected to and disconnected from each otherby a fifth clutch.

The third rotary element of the third planetary gear set and the secondrotary element of the fourth planetary gear set may be connected to anddisconnected from each other by a second clutch, and the third rotaryelement of the third planetary gear set and the third rotary element ofthe fourth planetary gear set may be connected to and disconnected fromeach other by a sixth clutch.

The first planetary gear set, the second planetary gear set, the thirdplanetary gear set, and the fourth planetary gear set may besequentially arranged in an axial direction.

The friction members may include a first clutch disposed for connectingand disconnecting the second rotary element of the second planetary gearset and the output shaft, a second clutch disposed for connecting anddisconnecting the third rotary element of the third planetary gear setand the second rotary element of the fourth planetary gear set, a thirdclutch disposed for connecting and disconnecting the second rotaryelement of the first planetary gear set and a transmission case, afourth clutch disposed for connecting and disconnecting the secondrotary element of the first planetary gear set and the third rotaryelement of the third planetary gear set, a fifth clutch disposed forconnecting and disconnecting the third rotary element of the secondplanetary gear set and the third rotary element of the fourth planetarygear set, and a sixth clutch disposed for connecting and disconnectingthe third rotary element of the third planetary gear set and the thirdrotary element of the fourth planetary gear set.

According to various aspects of the present invention, a transmissionfor a vehicle may include a first planetary gear set, a second planetarygear set, a third planetary gear set, and a fourth planetary gear seteach including three rotary elements, an input shaft connected to afirst rotary element of the first planetary gear set and a second rotaryelement of the third planetary gear set, a first shaft connecting asecond rotary element of the first planetary gear set, a third clutch,and a fourth clutch, a second shaft connecting a third rotary element ofthe first planetary gear set, a second rotary element of the secondplanetary gear set, and a first clutch, a third shaft connecting a thirdrotary element of the third planetary gear set, a second clutch, thefourth clutch, and a sixth clutch, a fourth shaft connecting a thirdrotary element of the second planetary gear set and a fifth clutch, afifth shaft connecting a third rotary element of the fourth planetarygear set, the fifth clutch, and the sixth clutch, a sixth shaftconnecting a first rotary element of the third planetary gear set and afirst rotary element of the fourth planetary gear set, an output shaftconnecting a second rotary element of the fourth planetary gear set, thefirst clutch, and the second clutch, and a transmission case connectedwith a first rotary element of the second planetary gear set and thethird clutch.

The first clutch may be disposed for connecting and disconnecting thesecond shaft and the output shaft, the second clutch may be disposed forconnecting and disconnecting the third shaft and the output shaft, thethird clutch may be disposed for connecting and disconnecting the firstshaft and the transmission case, the fourth clutch may be disposed forconnecting and disconnecting the first shaft and the third shaft, thefifth clutch may be disposed for connecting and disconnecting the fourthshaft and the fifth shaft, and the sixth clutch may be disposed forconnecting and disconnecting the third shaft and the fifth shaft.

The first clutch may be disposed for connecting and disconnecting thesecond rotary element of the second planetary gear set and the outputshaft, the second clutch may be disposed for connecting anddisconnecting the third rotary element of the third planetary gear setand the second rotary element of the fourth planetary gear set, thethird clutch may be disposed for connecting and disconnecting the secondrotary element of the first planetary gear set and the transmissioncase, the fourth clutch may be disposed for connecting and disconnectingthe second rotary element of the first planetary gear set and the thirdrotary element of the third planetary gear set, the fifth clutch may bedisposed for connecting and disconnecting the third rotary element ofthe second planetary gear set and the third rotary element of the fourthplanetary gear set, and the sixth clutch may be disposed for connectingand disconnecting the third rotary element of the third planetary gearset and the third rotary element of the fourth planetary gear set.

As described above, since the rotary elements of the first, second,third, and fourth planetary gear sets are selectivelyconnected/disconnected by a plurality of clutches, their rotationalspeeds and directions are changed and shifting is performed accordingly.Therefore, a vehicle can be driven with the gear ratios of ten or moresteps of forward shifting and one step of reverse shifting. Therefore,it is possible to improve fuel efficiency by implementing multiple stepsof shifting and improve vehicle driving comfort by using operatingpoints in a low RPM range of an engine.

It is understood that the term “vehicle” or “vehicular” or other similarterms as used herein is inclusive of motor vehicles in general such aspassenger automobiles including sports utility vehicles (SUV), buses,trucks, various commercial vehicles, watercraft including a variety ofboats and ships, aircraft, and the like, and includes hybrid vehicles,electric vehicles, plug-in hybrid electric vehicles, hydrogen-poweredvehicles and other alternative fuel vehicles (e.g., fuel derived fromresources other than petroleum). As referred to herein, a hybrid vehicleis a vehicle that has two or more sources of power, for example, bothgasoline-powered and electric-powered vehicles.

The methods and apparatuses of the present invention have other featuresand advantages which will be apparent from or are set forth in moredetail in the accompanying drawings, which are incorporated herein, andthe following Detailed Description, which together serve to explaincertain principles of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram schematically showing the structure of an exemplarytransmission for a vehicle according to the present invention.

FIG. 2 is a table showing operation in each range by an exemplarytransmission for a vehicle according to the present invention.

It should be understood that the appended drawings are not necessarilyto scale, presenting a somewhat simplified representation of variousfeatures illustrative of the basic principles of the invention. Thespecific design features of the present invention as disclosed herein,including, for example, specific dimensions, orientations, locations,and shapes will be determined in part by the particular intendedapplication and use environment.

DETAILED DESCRIPTION

Reference will now be made in detail to various embodiments of thepresent invention(s), examples of which are illustrated in theaccompanying drawings and described below. While the invention(s) willbe described in conjunction with exemplary embodiments, it will beunderstood that the present description is not intended to limit theinvention(s) to those exemplary embodiments. On the contrary, theinvention(s) is/are intended to cover not only the exemplaryembodiments, but also various alternatives, modifications, equivalentsand other embodiments, which may be included within the spirit and scopeof the invention as defined by the appended claims.

A transmission for a vehicle according to various embodiments of thepresent invention largely includes a first planetary gear set PG1, asecond planetary gear set PG2, a third planetary gear set PG3, and afourth planetary gear set PG4, and the planetary gear sets each mayinclude three rotary elements, that is, first, second, and third rotaryelements.

Referring to FIG. 1, the first rotary element of the first planetarygear set PG1 may be connected to an input shaft INPUT. For example, thefirst rotary element of the first planetary gear set PG1 may be a firstsun gear S1 and the first sun gear S1 may operate as a constant inputelement by being directly connected to the input shaft INPUT.

The second rotary element of the first planetary gear set PG1 mayoperate as a selectively-fixed element. For example, the second rotaryelement of the first planetary gear set PG1 may be a first carrier CR1and the first carrier CR1 can be connected/disconnected to/from atransmission case CS by a friction member.

The second rotary element of the first planetary gear set PG1 may beselectively connected with the third rotary element of the thirdplanetary gear set PG3. For example, the third rotary element of thethird planetary gear set PG3 may be a third ring gear R3, and the firstcarrier CR1 and the third ring gear R3 can be connected/disconnectedto/from each other by a friction member.

The third rotary element of the first planetary gear set PG1 may beconnected with the second rotary element of the second planetary gearset PG2. For example, the third rotary element of the first planetarygear set PG1 may be a first ring gear R1 and the second rotary elementof the second planetary gear set PG2 may be a second carrier CR2, so thefirst ring gear R1 and the second carrier CR2 can be directly connectedto each other.

The first rotary element of the second planetary gear set PG2 mayoperate as a fixed element. For example, the first rotary element of thesecond planetary gear set PG1 may be a second sun gear S2 and the secondsun gear S2 may operate as a constant fixed element by being directlyconnected to the transmission case CS.

The second rotary element of the second planetary gear set PG2 may beselectively connected to the output shaft OUTPUT. For example, thesecond rotary element of the second planetary gear set PG2 may be asecond carrier CR2, and the second carrier CR2 and the output shaftOUTPUT can be connected/disconnected to/from each other by a frictionmember.

The third rotary element of the second planetary gear set PG2 may beselectively connected with the third rotary element of the fourthplanetary gear set PG4. For example, the third rotary element of thesecond planetary gear set PG2 may be a second ring gear R2 and the thirdrotary element of the fourth planetary gear set PG4 may be a fourth ringgear R4, so the second ring gear R2 and the fourth ring gear R4 can beconnected/disconnected to/from each other by a friction member.

The first rotary element of the third planetary gear set PG3 may beconnected with the first rotary element of the fourth planetary gear setPG4. For example, the first rotary element of the third planetary gearset PG3 may be a third sun gear S3 and the first rotary element of thefourth planetary gear set PG4 may be a fourth sun gear S4, so the thirdsun gear S3 and the fourth sun gear S4 can be directly connected to eachother.

The second rotary element of the third planetary gear set PG3 may beconnected to the input shaft INPUT. For example, the second rotaryelement of the third planetary gear set PG3 may be a third carrier CR3and the third carrier CR3 may operate as a constant input element bybeing directly connected to the input shaft INPUT.

The third rotary element of the third planetary gear set PG3 may beselectively connected with the second rotary element of the fourthplanetary gear set PG4. For example, the third rotary element of thethird planetary gear set PG3 may be a third ring gear R3 and the secondrotary element of the fourth planetary gear set PG4 may be a fourthcarrier CR4, so the third ring gear R3 and the fourth carrier CR4 can beconnected/disconnected to/from each other by a friction member.

The third rotary element of the third planetary gear set PG3 may beselectively connected with the third rotary element of the fourthplanetary gear set PG4. For example, the third rotary element of thefourth planetary gear set PG4 may be a fourth ring gear R4, and thethird ring gear R3 and the fourth ring gear R4 can beconnected/disconnected to/from each other by a friction member.

The second rotary element of the fourth planetary gear set PG4 may beconnected to the output shaft OUTPUT. For example, the second rotaryelement of the fourth planetary gear set PG4 may be a fourth carrier CR4and the fourth carrier CR4 may operate as a constant output element bybeing directly connected to the output shaft OUTPUT.

In the present invention, the first planetary gear set PG1, secondplanetary gear set PG2, third planetary gear set PG3, and fourthplanetary gear set PG4 may be sequentially arranged in the axialdirection of the input shaft INPUT and the output shaft OUTPUT. Further,all of the first planetary gear set PG1, second planetary gear set PG2,third planetary gear set PG3, and fourth planetary gear set PG4 may besingle pinion planetary gear sets.

The present invention may further include a plurality of frictionmembers connected to at least one or more of the rotary elements of theplanetary gear sets and controlling rotation of the rotary elements. Thefriction members may be first, second, third, fourth, fifth, and sixthclutches C1, C2, C3, C4, C5, and C6.

In detail, the first clutch C1 may be disposed forconnecting/disconnecting the second carrier CR1, which is the secondrotary element of the second planetary gear set PG2, and the outputshaft OUTPUT.

The second clutch C2 may be disposed for connecting/disconnecting thethird ring gear R3 that is the third rotary element of the thirdplanetary gear set PG3 and the fourth carrier CR4 that is the secondrotary element of the fourth planetary gear set PG4.

The third clutch C3 may be disposed for connecting/disconnecting thefirst carrier CR1, which is the second rotary element of the firstplanetary gear set PG1, and the transmission case CS.

The fourth clutch C4 may be disposed for connecting/disconnecting thefirst carrier CR1 that is the second rotary element of the firstplanetary gear set PG1 and the third ring gear R3 that is the thirdrotary element of the third planetary gear set PG3.

The fifth clutch C5 may be disposed for connecting/disconnecting thesecond ring gear R2 that is the third rotary element of the secondplanetary gear set PG2 and the fourth ring gear R4 that is the thirdrotary element of the fourth planetary gear set PG4.

The sixth clutch C6 may be disposed for connecting/disconnecting thethird ring gear R3 that is the third rotary element of the thirdplanetary gear set PG3 and the fourth ring gear R4 that is the thirdrotary element of the fourth planetary gear set PG4.

On the other hand, the rotary elements of the planetary gear sets may beconnected through the input shaft INPUT, a first shaft A1 to a sixthshaft A6, and the output shaft OUTPUT.

Referring to FIG. 1, the first rotary element of the first planetarygear set PG1 and the second rotary element of the third planetary gearset PG3 may be directly connected to the input shaft INPUT.

The second rotary element of the first planetary gear set PG1, a firstside of the third clutch C3, and a first side of the fourth clutch C4may be connected to the first shaft A1.

The third rotary element of the first planetary gear set PG1, the secondrotary element of the second planetary gear set PG2, and a first side ofthe first clutch C1 may be connected to the second shaft A2.

The third rotary element of the third planetary gear set PG3, a firstside of the second clutch C2, a second side of the fourth clutch C4, anda first side of the sixth clutch C6 may be connected to the third shaftA3.

The third rotary element of the second planetary gear set PG2 and afirst side of the fifth clutch C5 may be connected to the fourth shaftA4.

The third rotary element of the fourth planetary gear set PG4, a secondside of the fifth clutch C5, and a second side of the sixth clutch C6may be connected to the fifth shaft A5.

The first rotary element of the third planetary gear set PG3 and thefirst rotary element of the fourth planetary gear set PG4 may beconnected to the sixth shaft A6.

The second rotary element of the fourth planetary gear set PG4, a secondside of the first clutch C1, and a second side of the second clutch C2may be connected to the output shaft OUTPUT.

The first rotary element of the second planetary gear set PG2 and asecond side of the third clutch C3 may be connected to the transmissioncase CS.

For example, the first clutch C1 may be disposed forconnecting/disconnecting the second shaft A2 and the output shaftOUTPUT, the second clutch C2 may be disposed forconnecting/disconnecting the third shaft A3 and the output shaft OUTPUT,and the third clutch C3 may be disposed for connecting/disconnecting thefirst shaft A1 and the transmission case CS.

Further, the fourth clutch C4 may be disposed forconnecting/disconnecting the first shaft A1 and the third shaft A3, thefifth clutch C5 may be disposed between the fourth shaft A4 and thefifth shaft A5, and the sixth clutch C6 may be disposed forconnecting/disconnecting the third shaft A3 and the fifth shaft A5.

FIG. 2 is a table showing operation in each range by a transmission fora vehicle according to various embodiments of the present invention, inwhich, for example, in order to implement a 1-range gear ratio, thesecond clutch C2, third clutch C3, and fifth clutch C5 may be connectedand all other friction members may be disconnected.

In order to implement a 2-range gear ratio, the third clutch C3, fourthclutch C4, fifth clutch C5 may be connected and all other frictionmembers may be disconnected. Further, as for the other ranges, a vehiclecan be driven with the gear ratios corresponding to the ranges byconnecting/disconnecting, as shown in the table.

As described above, since the rotary elements of the first, second,third, and fourth planetary gear sets PG1, PG2, PG3, and PG4 areselectively connected/disconnected by a plurality of clutches, theirrotational speeds and directions are changed and shifting is performedaccordingly. Therefore, a vehicle can be driven with the gear ratios often or more steps of forward shifting and one step of reverse shifting.Therefore, it is possible to improve fuel efficiency by implementingmultiple steps of shifting and improve vehicle driving comfort by usingoperating points in a low RPM range of an engine.

The foregoing descriptions of specific exemplary embodiments of thepresent invention have been presented for purposes of illustration anddescription. They are not intended to be exhaustive or to limit theinvention to the precise forms disclosed, and obviously manymodifications and variations are possible in light of the aboveteachings. The exemplary embodiments were chosen and described in orderto explain certain principles of the invention and their practicalapplication, to thereby enable others skilled in the art to make andutilize various exemplary embodiments of the present invention, as wellas various alternatives and modifications thereof. It is intended thatthe scope of the invention be defined by the Claims appended hereto andtheir equivalents.

What is claimed is:
 1. A transmission for a vehicle, comprising: a firstplanetary gear set, a second planetary gear set, a third, planetary gearset, and a fourth planetary gear set each including three rotaryelements; and a plurality of friction members, wherein the firstplanetary gear set includes: a first rotary element connected to aninput shaft; a second rotary element operating as a selectively-fixedelement and selectively connected with a third rotary element of thethird planetary gear set; and a third rotary element connected with asecond rotary element of the second planetary gear set, the secondplanetary gear set includes: a first rotary member operating as a fixedelement; the second rotary element selectively connected to an outputshaft; and a third rotary element selectively connected with a thirdrotary element of the fourth planetary gear set, the third planetarygear set includes: a first rotary element connected with a first rotaryelement of the fourth planetary gear set; a second rotary elementconnected to an input shaft; and a third rotary element selectivelyconnected to a second rotary element of the fourth planetary gear setand the third rotary element of the fourth planetary gear set, thefourth planetary gear set includes the second rotary element connectedto an output shaft, and the friction members are connected to at leastone or more of the rotary elements of the planetary gear sets andcontrol rotation of the rotary elements.
 2. The transmission of claim 1,wherein in the first planetary gear set, the first rotary element is afirst sun gear, the second rotary element is a first carrier, and thethird rotary element is a first ring gear, in the second planetary gearset, the first rotary element is a second sun gear, the second rotaryelement is a second carrier, and the third rotary element is a secondring gear, in the third planetary gear set, the first rotary element isa third sun gear, the second rotary element is a third carrier, and thethird rotary element is a third ring gear, and in the fourth planetarygear set, the first rotary element is a fourth sun gear, the secondrotary element is a fourth carrier, and the third rotary element is afourth ring gear.
 3. The transmission of claim 2, wherein the secondrotary element of the first planetary gear set is connected to anddisconnected from a transmission case by a third clutch, and the secondrotary element of the first planetary gear set and the third rotaryelement of the third planetary gear set are connected to anddisconnected from each other by a fourth clutch.
 4. The transmission ofclaim 2, wherein the first rotary element of the second planetary gearset is connected to a transmission case, the second rotary element ofthe second planetary gear set is connected to and disconnected from theoutput shaft by a first clutch, and the third rotary element of thesecond planetary gear set and the third rotary element of the fourthplanetary gear set are connected to and disconnected from each other bya fifth clutch.
 5. The transmission of claim 2, wherein the third rotaryelement of the third planetary gear set and the second rotary element ofthe fourth planetary gear set are connected to and disconnected fromeach other by a second clutch, and the third rotary element of the thirdplanetary gear set and the third rotary element of the fourth planetarygear set are connected to and disconnected from each other by a sixthclutch.
 6. The transmission of claim 2, wherein the first planetary gearset, the second planetary gear set, the third planetary gear set, andthe fourth planetary gear set are sequentially arranged in an axialdirection.
 7. The transmission of claim 1, wherein the friction membersinclude: a first clutch disposed for connecting and disconnecting thesecond rotary element of the second planetary gear set and the outputshaft; a second clutch disposed for connecting and disconnecting thethird rotary element of the third planetary gear set and the secondrotary element of the fourth planetary gear set; a third clutch disposedfor connecting and disconnecting the second rotary element of the firstplanetary gear set and a transmission case; a fourth clutch disposed forconnecting and disconnecting the second rotary element of the firstplanetary gear set and the third rotary element of the third planetarygear set; a fifth clutch disposed for connecting and disconnecting thethird rotary element of the second planetary gear set and the thirdrotary element of the fourth planetary gear set; and a sixth clutchdisposed for connecting and disconnecting the third rotary element ofthe third planetary gear set and the third rotary element of the fourthplanetary gear set.
 8. A transmission for a vehicle, comprising: a firstplanetary gear set, a second planetary gear set, a third planetary gearset, and a fourth planetary gear set each including three rotaryelements; an input shaft connected to a first rotary element of thefirst planetary gear set and a second rotary element of the thirdplanetary gear set; a first shaft connecting a second rotary element ofthe first planetary gear set, a third clutch, and a fourth clutch; asecond shaft connecting a third rotary element of the first planetarygear set, a second rotary element of the second planetary gear set, anda first clutch; a third shaft connecting a third rotary element of thethird planetary gear set, a second clutch, the fourth clutch, and asixth clutch; a fourth shaft connecting a third rotary element of thesecond planetary gear set and a fifth clutch; a fifth shaft connecting athird rotary element of the fourth planetary gear set, the fifth clutch,and the sixth clutch; a sixth shaft connecting a first rotary element ofthe third planetary gear set and a first rotary element of the fourthplanetary gear set; an output shaft connecting a second rotary elementof the fourth planetary gear set, the first clutch, and the secondclutch; and a transmission case connected with a first rotary element ofthe second planetary gear set and the third clutch.
 9. The transmissionof claim 8, wherein the first clutch is disposed for connecting anddisconnecting the second shaft and the output shaft, the second clutchis disposed for connecting and disconnecting the third shaft and theoutput shaft, the third clutch is disposed for connecting anddisconnecting the first shaft and the transmission case, the fourthclutch is disposed for connecting and disconnecting the first shaft andthe third shaft, the fifth clutch is disposed for connecting anddisconnecting the fourth shaft and the fifth shaft, and the sixth clutchis disposed for connecting and disconnecting the third shaft and thefifth shaft.
 10. The transmission of claim 9, wherein the first clutchis disposed for connecting and disconnecting the second rotary elementof the second planetary gear set and the output shaft, the second clutchis disposed for connecting and disconnecting the third rotary element ofthe third planetary gear set and the second rotary element of the fourthplanetary gear set, the third clutch is disposed for connecting anddisconnecting the second rotary element of the first planetary gear setand the transmission case, the fourth clutch is disposed for connectingand disconnecting the second rotary element of the first planetary gearset and the third rotary element of the third planetary gear set, thefifth clutch is disposed for connecting and disconnecting the thirdrotary element of the second planetary gear set and the third rotaryelement of the fourth planetary gear set, and the sixth clutch isdisposed for connecting and disconnecting the third rotary element ofthe third planetary gear set and the third rotary element of the fourthplanetary gear set.